The invention relates to a pedal locking and unlocking device for mortar and plaster mixing machines, consisting essentially of mainly cylindrical drums, inside which a rotating shaft equipped with appropriate blades and activated by an electric or gas motor, mixes the mortar contained therein.
The unloading of the mixed substance occurs by gravity by manually rotating the drum around its supporting axle. During the mixing operation both the rotating shaft and the moving substance inside the drum exert a thrust which tends to make the drum rotate also; it is, therefore, necessary to prevent said rotation and for this reason the drum is locked to its stands by means of latches or similar means. When the unloading operation is performed, the operator removes the locking means and operates the lever which causes the drum containing the mortar to rotate.